1. Field of the Invention
The present invention relates to an image processing apparatus that processes an image signal from an image pickup element including a plurality of pixels for one microlens.
2. Description of the Related Art
Previously, a technology that obtains pupil division images by an image pickup element including a plurality of pixels for one microlens and that performs focus detection using a phase difference of the two obtained pupil division images has been known. For example, Japanese Patent Laid-Open No. 2001-83407 discloses an image pickup apparatus that calculates a phase difference based on pupil division images to perform the focus detection. In Japanese Patent Laid-Open No. 2001-83407, all output values of a plurality of pixels that correspond to the same microlens are added to be treated as one pixel, and thus a pixel array that is equivalent to a conventional one is configured.
However, in the configuration as disclosed in Japanese Patent Laid-Open No. 2001-83407, there is a possibility that each of the plurality of pixels corresponding to the same microlens reaches a saturation level. In other words, when a specific pixel reaches the saturation level, charges permitted in the conventional configuration where one pixel corresponds to one microlens may be leaked from the specific pixel to be lost.